fix: update purchase page link

[donnyquixotic]

Fixes #769

Test scenarios

• link on testnet opens faucet page
• links for evm mainnet and native link to new buy page

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have cleaned up the code in the areas my change touches
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings
• I have removed any unnecessary console messages

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